The invention relates to universal joints. More particularly, the invention relates to a ball triplan constant velocity joint centering spring.
Triplan versions of tripod constant velocity joints have been used in the automotive industry for numerous years. The triplan constant velocity joint was developed to overcome shudder problems which are inherent in the standard design tripod joints.
A standard tripod joint has a bell shaped outer member having an internal cavity, an inner member, three annular rollers, and a plurality of needles. Each roller is positioned around a respective radially extending trunnion of the inner member. Journaled between the rollers and the trunnions are the plurality of needles. This arrangement enables for free rotation of the rollers relative to the trunnions. The inner member, rollers and needles are positioned in the internal cavity formed in the outer member. When operating at a zero degree angle, each roller rolls along a respective sidewall of the internal cavity of the outer member. This rolling action causes a low axial force, generated by rolling friction, to be exerted between the rollers and the outer member.
When the tripod joint is operating at an angle, the plane of the roller is skewed relative to the plane of the internal cavity. This skewed relationship causes a combination of rolling and sliding action of the roller relative to the outer member. As the angle of joint operation increases, the amount of sliding of the roller increases and the amount of rolling of the roller decreases.
This sliding action of the roller relative to the outer member generates a three per revolution pulsating axial load. This load can be transmitted through the outer member to other components within the vehicle and eventually will become noticeable and objectionable to the individuals riding in the vehicle. This objectionable vibration has been termed "shudder".
The triplan joints are designed to reduce or eliminate this shudder phenomena. The triplan joints separate the components within the joints which are responsible for accommodating the angular and translational movement of the joints. This separation of responsibilities allows the joints to utilize rolling friction instead of sliding friction to accomplish transitional movement of the joints when the joints are operating at an angle. With respect to frictional loading, rolling friction is significantly lower than sliding friction, and thus the magnitude of the axial load generated between the roller and the outer member is significantly reduced. This has the effect of reducing or eliminating shudder.
Unfortunately the amount of rolling travel available to these types of triplan joints is limited by the design of their internal components. In actual vehicle use, the travel requirement of the vehicle is beyond the rolling travel capabilities of these joints. Triplan joints have a specific amount of rolling travel available. This rolling travel is sufficient to accommodate engine movement and vibration as well as smaller suspension movements. When these triplan joints reach the end of their rolling travel, any additional travel is accommodated by a sliding action. Thus, the triplan joint, during sliding travel, has the same problems associated with conventional tripod joints.
This travel limitation problem is compounded by the migration of the internal components during operation of the joint. This migration of the internal components means that the maximum amount of rolling travel required is not always available to the joint. Thus it is not possible to determine or predict when rolling travel will be available.
In an attempt to overcome these problems of limited rolling travel, earlier designs of triplan joints incorporated a positioning mechanism for the internal components. This positioning mechanism was designed to insure that the maximum amount of rolling plunge was available to the joint at all times. Prior attempts at a positioning device have either been too expensive, too complicated for volume production or they have been found to be unreliable.
Accordingly, it is desirous to have a positioning means for a ball triplan joint which is relatively inexpensive and reliable.